An Observational Study of a Severe Squall Line Crossing Hong Kong on 15 March 2025 Based on Radar-Retrieved Three-Dimensional Winds and Flight Data

The present paper reports for the first time the comparison of radar-derived eddy dissipation rate (EDR) and vertical velocity with measurements from six aircraft for an intense squall line crossing Hong Kong. The study objectives are three-fold: (i) to characterise the structural dynamics of the in...

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Main Authors: Pak-wai Chan, Ying-wa Chan, Ping Cheung, Man-lok Chong
Format: Article
Language:English
Published: MDPI AG 2025-08-01
Series:Applied Sciences
Subjects:
Online Access:https://www.mdpi.com/2076-3417/15/15/8562
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author Pak-wai Chan
Ying-wa Chan
Ping Cheung
Man-lok Chong
author_facet Pak-wai Chan
Ying-wa Chan
Ping Cheung
Man-lok Chong
author_sort Pak-wai Chan
collection DOAJ
description The present paper reports for the first time the comparison of radar-derived eddy dissipation rate (EDR) and vertical velocity with measurements from six aircraft for an intense squall line crossing Hong Kong. The study objectives are three-fold: (i) to characterise the structural dynamics of the intense squall line; (ii) to identify the dynamical change in EDR and vertical velocity during its eastward propagation across Hong Kong with a view to gaining insight into the intensity change of the squall line and the severity of its impact on aircraft flying near it; (iii) to carry out quantitative comparison of EDR and vertical velocity derived from remote sensing instruments, i.e., weather radars and in situ measurements from aircraft, so that the quality of the former dataset can be evaluated by the latter. During the passage of the squall line and taking reference of the radar reflectivity, vertical circulation and the subsiding flow at the rear, it appeared to be weakening in crossing over Hong Kong, possibly due to land friction by terrain and urban morphology. This is also consistent with the maximum gusts recorded by the dense network of ground-based anemometers in Hong Kong. However, from the EDR and the vertical velocity of the aircraft, the weakening trend was not very apparent, and rather severe turbulence was still recorded by the aircraft flying through the squall line into the region with stratiform precipitation when the latter reached the eastern coast of Hong Kong. In general, the radar-based and the aircraft-based EDRs are consistent with each other. The radar-retrieved maximum vertical velocity may be smaller in magnitude at times, possibly arising from the limited spatial and temporal resolutions of the aircraft data. The results of this paper could be a useful reference for the development of radar-based turbulence products for aviation applications.
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spelling doaj-art-9f50ef0b2f7740a3b5fcd7f369306ffb2025-08-20T04:00:49ZengMDPI AGApplied Sciences2076-34172025-08-011515856210.3390/app15158562An Observational Study of a Severe Squall Line Crossing Hong Kong on 15 March 2025 Based on Radar-Retrieved Three-Dimensional Winds and Flight DataPak-wai Chan0Ying-wa Chan1Ping Cheung2Man-lok Chong3Hong Kong Observatory, Hong Kong, ChinaHong Kong Observatory, Hong Kong, ChinaHong Kong Observatory, Hong Kong, ChinaHong Kong Observatory, Hong Kong, ChinaThe present paper reports for the first time the comparison of radar-derived eddy dissipation rate (EDR) and vertical velocity with measurements from six aircraft for an intense squall line crossing Hong Kong. The study objectives are three-fold: (i) to characterise the structural dynamics of the intense squall line; (ii) to identify the dynamical change in EDR and vertical velocity during its eastward propagation across Hong Kong with a view to gaining insight into the intensity change of the squall line and the severity of its impact on aircraft flying near it; (iii) to carry out quantitative comparison of EDR and vertical velocity derived from remote sensing instruments, i.e., weather radars and in situ measurements from aircraft, so that the quality of the former dataset can be evaluated by the latter. During the passage of the squall line and taking reference of the radar reflectivity, vertical circulation and the subsiding flow at the rear, it appeared to be weakening in crossing over Hong Kong, possibly due to land friction by terrain and urban morphology. This is also consistent with the maximum gusts recorded by the dense network of ground-based anemometers in Hong Kong. However, from the EDR and the vertical velocity of the aircraft, the weakening trend was not very apparent, and rather severe turbulence was still recorded by the aircraft flying through the squall line into the region with stratiform precipitation when the latter reached the eastern coast of Hong Kong. In general, the radar-based and the aircraft-based EDRs are consistent with each other. The radar-retrieved maximum vertical velocity may be smaller in magnitude at times, possibly arising from the limited spatial and temporal resolutions of the aircraft data. The results of this paper could be a useful reference for the development of radar-based turbulence products for aviation applications.https://www.mdpi.com/2076-3417/15/15/8562squall linevertical velocityeddy dissipation rate
spellingShingle Pak-wai Chan
Ying-wa Chan
Ping Cheung
Man-lok Chong
An Observational Study of a Severe Squall Line Crossing Hong Kong on 15 March 2025 Based on Radar-Retrieved Three-Dimensional Winds and Flight Data
Applied Sciences
squall line
vertical velocity
eddy dissipation rate
title An Observational Study of a Severe Squall Line Crossing Hong Kong on 15 March 2025 Based on Radar-Retrieved Three-Dimensional Winds and Flight Data
title_full An Observational Study of a Severe Squall Line Crossing Hong Kong on 15 March 2025 Based on Radar-Retrieved Three-Dimensional Winds and Flight Data
title_fullStr An Observational Study of a Severe Squall Line Crossing Hong Kong on 15 March 2025 Based on Radar-Retrieved Three-Dimensional Winds and Flight Data
title_full_unstemmed An Observational Study of a Severe Squall Line Crossing Hong Kong on 15 March 2025 Based on Radar-Retrieved Three-Dimensional Winds and Flight Data
title_short An Observational Study of a Severe Squall Line Crossing Hong Kong on 15 March 2025 Based on Radar-Retrieved Three-Dimensional Winds and Flight Data
title_sort observational study of a severe squall line crossing hong kong on 15 march 2025 based on radar retrieved three dimensional winds and flight data
topic squall line
vertical velocity
eddy dissipation rate
url https://www.mdpi.com/2076-3417/15/15/8562
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